A semiconductor light emitting device such as a light emitting diode (LED) or the like is a device emitting light through a material contained therein. LEDs convert energy generated through electron-hole recombination occurring at p-n junctions between p-type and n-type semiconductors into light to be emitted therefrom. Such LEDs have been widely used as light sources in lighting devices, display devices, and the like, and the development thereof is being accelerated.
In particular, as mobile phone keypads, turn signal lamps, camera flashes and the like using GaN-based LEDs are commercialized, the development of general lighting devices using LEDs is being actively undertaken. As the use of LEDs is extended from small portable devices to large, high output, and high efficiency products such as the backlight units of large screen TVs, the headlights of vehicles, general lighting devices, light sources having the characteristics required by the corresponding products have been demanded.
As the use of semiconductor light emitting devices is increased, a method of improving light extraction efficiency thereof is particularly beneficial.